• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.27-39
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• 2009

The 1st Incheon Rapid Transit Line opened in October, 1999. However, the current development plans for areas near stations do not involve plans for the both urban planning and transportation together. As the focus on only the aspect of installing a new transportation mode, the developments even make the problems such as reckless development and traffic congestion gets worse. It is required to analyse status of the current land uses and land use plans in the future and consider distribution of functions of the areas near stations and aims of development plans so as to harmonize the functions of each region in view of making balance in the whole city. The aims of developments of areas near stations has to focus on the study follows steps to find and suggest aims and strategies for the revitalization plan for areas near stations with considering the both transportation and land uses together. The plans for the areas near stations of the Incheon 1st Rapid Transit Line are analysed and then the features and rational strategies are derived. The impact is analysed as applying the development strategies derived from the step into the areas near the stations of Incheon 1st Rapid Transit line.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.4
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• pp.439-447
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• 2008

One of the key elements in efforts to minimize noise radiation from a powertrain is the knowledge of the main radiating component and the relation between the surface vibration of a powertrain and the sound pressure. In this research, the powertrain model is developed based on FEM(finite element method). This model is applied to the prediction of the vibration of a powertrain by using ADAMS and the radiation noise by using BEM(boundary element method). According to this numerical analysis, the surface vibration of a powertrain is investigated as a source of radiated noise. This surface vibration is caused by the 1st order natural vibration of the cylinder block and its mode shape is the torsion mode. Therefore, this mode shape is modified to reduce the surface vibration of the powertrain. The radiation noise of the modified powertrain is also reduced to $5{\sim}12\;dB$. This modification is very successful for the noise reduction based on the CAE technology.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.657-668
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• 2021

In this study, a relationship between the resonance frequency ratio and Poisson's ratio was proposed that can be used to directly determine the elastic constants. Using this relationship, the frequency ratio between the 1st bending mode and 2nd bending mode for any rectangular Timoshenko beam can be directly estimated and used to determine the elastic constants efficiently. The exact solution of the Timoshenko beam vibration frequency equation under free-free boundary conditions was determined with an accurate shear shape factor. The highest percent difference for the frequency ratio between the theoretical values and the estimated values for all the beam dimensions studied was less than 0.02%. The proposed equations were used to obtain the elastic constants of beams with different material properties and dimensions using the first two measured transverse bending frequencies. Results show that using the equations proposed in this study, the Young's modulus and Poisson's ratio of rectangular Timoshenko beams can be determined more efficiently and accurately than those obtained from industry standards such as ASTM E1876-15 without the need to test the torsional vibration.

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.1
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• pp.19-28
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• 2000

Authors evaluated alterations of observable metabolite ratios between the cerebral lesion and the contralateral region related to the clinical symptomatic side in levodopa-treated Parkinson's disease (PD) and investigated correlation between age in patients with PD and metabolite ratios of the lesion. Patients with levodopa-treated PD (n = 54) and age-matched normal controls (n = 15) underwent magnetic resonance spectroscopy (MRS) examinations using a stimulated echo acquisition mode (STEAM) pulse sequence that provided 2$\times$2$\times$2 cm3 volume of interest in the selected regions of substantia nigra (SN) and putamed-globus pallidus (PG). To evaluate dependence of metabolite ratios on age, we divided into two groups (i.e., younger and older age). We quantitatively measured N-acetylaspartate (NAA), creatine (Cr), choline-containing compounds (Cho), inositols (Ins), and the sum of glutamate (Glx) and GABA levels and obtained proton metabolite ratios relative to Cr using a Marquart algorithm. Compared with the contralateral region, a significant neuronal laterality of the NAA/Cr ratio in the lesion of SN related to the clinical symptomatic side was established (P = 0.01), but was not established in the lesion of PG (P = 0.24). Also, Cho/Cr ratio tended toward significance in the lesion of SN (P = 0.07) and was statistically significant in the lesion of PG(P = 0.01). Compared with that in the younger age group, NAA/Cr ratio in the older age was decreased in the lesion of SN (P = 0.02), while NAA/Cr ratio was not statistically significant in the lesion of PG ( P = 0.21). Significant metabolic alterations of NAA/Cr and Cho/Cr ratios might be closely related with functional changes of neuropathological process in SN and PG of levodopa treated PD and could be a valuable finding for evaluation of the PD. A trend of NAA/Cr reduction, being statistically significant in older patients, could be indicative of more pronounced neuronal damage in the SN of the progressive PD.

• Journal of the Korean Magnetic Resonance Society
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• v.5 no.2
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• pp.99-109
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• 2001

Authors investigated neuronal changes of local cellular metabolism in the cerebral lesions of Parkinsonian symptomatic side between before and after stereotactic neurosurgery by follow-up 1H magnetic resonance spectroscopy (MRS). Patients with Parkinson's disease (PD) (n = 15) and age-matched normal controls (n = 15) underwen MRS examinations using a stimulated echo acquisition mode (STEAM) pulse sequence that provided 2${\times}$2${\times}$2 ㎤ (8ml) volume of interest in the regions of substantia nigra, thalamus, and lentiform nucleus. Spectral parameters were 20 ms TE, 2000 ms TR, 128 averages,2500 Hz spectral width, and 2048 data points. Raw data were processed by the SAGE data analysis package (GE Medical Systems). Peak areas of N-acetylaspartate (NAA), creatine (Cr), choline-containing compounds (Cho), inositols (Ins), and the sum (Glx) of glutamate and GABA were calculated by means of fitting the spectrum to a summation of Lorentzian curves using Marquardt algorithm. After blindly processed, we evaluated neuronal alterations of observable metabolite ratios between before and after stereotactic neurosurgery using Pearson product-moment analysis (SPSS, Ver. 6.0). A significant reduction of NAA/Cho ratio was observed in the cerebral lesion in substantia nigra of PD patient related to the symptomatic side after neurosurgery (P : 0.03). In thalamus, NAA/Cho ratio was also significantly decreased in the cerebral lesion including the electrode-surgical region (P : 0.03). A significant reduction of NAA/Cho ratio in lentiform nucleus was not oberved, but tended toward significant reduction after neurosurgery (P = 0.08). In particular, remarkable lactate signal was noted from the surgical thalamic lesions of 6 among 8 patients and internal segments of globus pallidus of 6 among 7 patients, respectively. Significant metabolic alterations of NAA/Cho ratio might reflect functional changes of neuropathological processes in the lesion of substantia nigra, thalamus, and lentiform nucleus, and could be a valuable finding fur evaluation of Parkinson's disease after neurosurgery. Increase of lactate signals, being remarkable in surgical lesions, could be consistent with a common consequence of neurosurgical necrosis. Thus, IH MRS could be a useful modality to evaluate the diagnostic and prognostic implications fur Parkinsons disease after functional neurosurgery.

• Neonatal Medicine
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• v.25 no.2
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• pp.78-84
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• 2018

Purpose: To investigate the hemodynamic risk factors for necrotizing enterocolitis (NEC), we analyzed the characteristics of descending aorta (DA) blood flow in preterm neonates, who later developed NEC. Methods: This was an observational case-control study on 53 preterm neonates at a tertiary referral center. Clinical and echocardiographic data were collected from 23 preterm neonates with NEC (NEC group), and compared with those of 30 preterm neonates without NEC (control group). Echocardiography was done at a median (interquartile range) of 5 (3-9) days after birth and 2 (1-2.5) days before the diagnosis of NEC. Results: Basic clinical characteristics including gestational age, birth weight, Apgar score, breast feeding status, use of umbilical catheters, and mode of invasive ventilator care were similar between the groups. Compared with the control group, the lowest diastolic velocity of DA was significantly decreased, whereas the diastolic reverse flow and the ratio of diastolic reverse to systolic forward flows were significantly increased in the NEC group. In addition, the resistive index (RI) of DA was significantly increased in the NEC group and showed a positive association with the development of NEC. Multivariate logistic regression analysis showed that increasing RI of DA was an independent risk factor for the development of NEC (P=0.008). Conclusion: Significant changes in DA flow characteristics including decreased diastolic velocity and increased diastolic reverse flow along with increased peripheral vascular resistance were observed before the development of NEC in preterm neonates. These findings may help clinicians stratify in advance neonates at a risk of developing NEC and may help improve outcomes in these neonates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.6 s.261
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• pp.718-724
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• 2007

Some of gas turbine model of 7F-Class has constructed and is operating with units domestically. Non-destructive testing (NDT) is one of the methods being used to inspect damage $1^{st}$ stage bucket and review damage trends. We also analyze damage configuration and microstructure according to material and compare with pape of electric power research institute (EPRI). The damaged mode could be determined by leveraging failure analysis. Especially, configuration uprate of bucket is not only to prevent damage during operation but also avoid domestic manufacturing by the competitors. Modifications were mainly concentrated on surfaces such as cooling hole and bucket tips. Analyzing of bucket damage, the earlier model of 7F-Class used with one cycle with equivalent operation hour (EOH), has various cracking of the bucket surface. Bucket damage of new model is centered on tip area (54%) as analyzed by EPRI research. We conclude that improving bucket configuration would increase repair rate on the bucket tip.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.19-22
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• 2004

The resonant planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 500 kHz, was designed and manufactured by using the planar core with large effective area and the flat copper lead frames for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a resonant converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 12 and 2 respectively. The self inductance of 1st winding was 33.2 ${\mu}H$, very low leakage inductance of 1.27 ${\mu}H$, and the coupling factor of 0.98 were obtained at switching frequency of 300 kHz. The high efficiency of 88.21 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.4
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• pp.319-325
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• 2007

In case of more than 50km baseline length, the correlation between receivers is reduced. Therefore, there are still some rooms for improvement of its positional accuracy. In this paper, the stochastic modeling of the ionospheric delay is applied and its effects are analyzed. The data processing has been performed by constructing a Kalman filter with states of positions, ambiguities, and the ionospheric delays in the double differenced mode. Considering the medium or long baseline length, both double differenced GPS phase and code observations are used as observables and LAMBDA has been applied to fix the ambiguities. The ionospheric delay is stochastically modeled by well-known 1st order Gauss-Markov process. And the correlation time and variation of 1st order Gauss-Markov process are calculated. This paper gives analyzed results of developed algorithm compared with commercial software and Bernese.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.3
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• pp.195-200
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• 1994

This experiment was undertaken to study the relationship between dry weight of plant(DW) and yield components. varietal differences in seasonal production at each of three cutting. and to classiQ them into some patterns of seasonal production in tall fescue varieties. The varieties examined were Barvetia. Fuego, Demeter. Safe, Barcel. Forager, Johnstone. Enforcer and Stef. The results obtained were as follows : 1. The Fuego and Barcel with high number of tiller per plant(NT) which had more dry wieght of plant(DW) than those of varieties with low number of tillers per plant(NT) at each cutting. 2. The dry weight of plant(DW) in 1st cutting indicated positive significant correlation with the number of tillers per plant(NT) and dry weight of a tiller(WT). But there was only positive correlation between the number of tillers per plant(NT) and dry weight of plant(DW) in 2nd and 3rd cutting. 3. Mean relative yield of each cutting were 3 1 %. 29.7% and 39.3% in 1st. 2nd and 3rd cutting, respectively. 4. Tall fescue varieties could be classified into 3 different seasonal growth patterns according to their mode of relative yield at each cutting. Barvetia, Fuego, Johnstone. Enforcer and Stef belong to the group of ABA with high relative yield in 1st and 3rd cutting. Demeter, Safe and Forager belong to the group of CBA with relative yield increased linearly up to 3rd cutting. And, Barcel belong to the group of BAB with high relative yield in 2nd cutting.